Biomedical Engineering Reference
In-Depth Information
(a)
(b)
20 nm
20 nm
(c)
(d)
FePt
(111)
CoFe
2
O
4
(311)
20 nm
20 nm
Figure 13.5
Transmission electron microscopy images of
as - synthesized nanoparticles. (a) 8 nm FePt; (b) 8 nm/8 nm
FePt/CoFe
2
O
4
; (c) 8 nm/10 nm FePt/CoFe
2
O
4
; (d) HRTEM of
as - synthesized 8 nm/8 nm FePt/CoFe
2
O
4
. Reproduced
with permission from Ref. [30]; © 2008,
American Chemical Society.
method facilitates a homogeneous distribution of the relevant elements within the
resultant nanoparticles upon molecular decomposition. The synthetic method
must be designed such that decomposition of the single-source precursor delivers
metal atoms with suffi cient energy to form the desired alloy with all undesired
precursor atoms readily removed from the system. Undesirable precursor atoms
can be displaced typically via a combination of secondary chemical reactions and/
or by supplying suffi cient thermal energy to remove them as volatile products.
Rutledge
et al
. [31] described the synthesis of FePt nanoparticles which exhibited
unexpectedly high room-temperature coercivity by the ultrasonication of toluene
solutions of the heteropolynuclear cluster complex, Pt
3
Fe
3
(CO)
15
, followed by
thermal annealing to obtain fct FePt nanoparticles. When the known polyhetero-
nuclear cluster complex, Pt
3
Fe
3
(CO)
15
[32], was dissolved in the presence of oleic
acid and oleylamine and sonicated under N
2
for 1 h, surface - passivated fcc FePt
